The resent invention relates to the automatic analyzer which uses reagent or the like to analyze the components of the specimen as objects of analysis, and particularly to the automatic analyzer provided with an agitator to ensure that reagent required for analysis of specimen components is mixed with the specimen.
To mix reagent with the specimen in the agitator of the conventional automatic analyzer, an agitating rod 61 having a spatula-shaped tip is inserted into the reaction vessel where reagent is mixed with the specimen, and the agitating rod is rotated or moved in reciprocating motion.
For example, the agitating rod 61 having a spatula-shaped tip is inserted into the reaction vessel 11 containing a mixture of reagent and specimen as shown in FIG. 9(a), and the agitating rod 61 is rotated by an actuator 60. Or the agitating rod 61 having a spatula-shaped tip is inserted into the reaction vessel 11 containing a mixture of reagent and specimen as shown in FIG. 9(b), and the agitating rod 61 is moved in reciprocating motion by an actuator 60.
When this conventional automatic analyzer is used, a trace amount of chemicals or specimens deposited on the agitating rod will cause a phenomenon called carry-over which affects the result of the next analysis. This requires some means to clean the agitating rod.
Official Gazette of Japanese Patent Laid-Open NO.311204/1997 discloses an example of using a piezoelectric element as dispensing nozzle cleaning means. The cleaning means disclosed in this Journal gives mechanical oscillation to the nozzle itself to remove reagent or specimen deposited on the dispensing nozzle. It uses oscillation of the piezoelectric element to improve nozzle cleaning effect. This is not effective as an agitating means to promote mixing between reagent and specimen.
To reduce physical loads of the specimen provider or to cut down system running costs for the automatic analyzer, efforts are made to reduce the amount of the specimen and reagent required for analysis of each item.
In this case, if the amount of the specimen and reagent is reduced in the reaction vessel having the same capacity as that of the conventional reaction vessel as shown in FIG. 10(b), the area which light to be measured passes by will be smaller than when the amount of the specimen and reagent shown in FIG. 10(a) is not reduce. This will result in reduced measuring accuracy.
To get an accurate measurement of the reduced amount of the specimen and reagent, it is necessary to reduce the capacity of the reaction vessel and to secure the liquid level of the specimen and reagent and light transmission area, as shown in FIG. 10(c).
However, it becomes difficult to physically insert and to reciprocate the agitating rod due to reduced capacity of the reaction vessel in case of the automatic analyzer using the reaction vessel having a reduced capacity, where the agitating rod having a spatula-shaped tip in the agitator to mix the reagent with the specimen is inserted into said reaction vessel to rotate the agitating rod or move it in reciprocating motion. Therefore, an agitation mechanism to agitate the reagent with the specimen without using the agitating rod becomes to be needed.
Furthermore, even if the agitating rod is cleaned, it is impossible to completely eliminate the phenomenon of carry-over where a trace amount of specimen or reagent is carried over to the next analysis. It is also impossible to eliminate the possibility of water for cleaning being brought into the reaction vessel by the agitating rod.
Said carry-over and transfer of cleaning water into the vessel will have some adverse effect on the result of analysis when the capacity of the reaction vessel is reduced and the quality of reagent and specimen is decreased.